John B. Davidson, a co-founder of the Children’s Theatre who later became known as a playwright, died Tuesday, Nov. 5, in Minneapolis. His death, at 81, came a week before his adaptation of “Cinderella” went into previews at the Children’s Theatre. The show has been a staple of the company’s repertory since the 1970s.

“His heart just gave out,” said Betsy Spitzer, his daughter.

Davidson is best known for “Cinderella,” which has been part of the company’s repertory since the 1970s, and “The Last Minstrel Show,” about the 1920 lynching of black circus workers falsely accused of rape in Duluth.

Born and reared in Minneapolis, Davidson graduated from Minneapolis Central High School. He served a spell in the U.S. Navy, according to his family, and then attended graduate school in theater at the University of Minnesota.

That is where he met up with some of the other co-founders of the Moppet Players, which would become the Children’s Theatre. Davidson served as managing director in the early company, said actor and singer Barbara Davidson, whom he married and divorced but with whom he remained cordial.

“He was acerbic and exacting,” she said. “He had very high standards for work, even if he didn’t always live up to them.”